1. Field of the Invention
The invention relates to a sighting system for a machine gun, such as an M2HB, M3 flexible, which is a 50 caliber machine gun. More specifically, the invention relates to a sighting system having a rear sight assembly which is adjustable for sighting in long-range and short-range targets and a front sight assembly.
2. Description of Related Art
Rear and front sights are presently used on machine guns for sighting long-range and short-range targets. In this respect, both the rear sight and the front sight are mounted on the receiver of the machine gun. The rear sight is mounted at the rear end of the machine gun and the front sight is mounted at the front of the machine gun, closer to the target.
One such arrangement involves a front sight that is in a fixed position. The front sight has an arc housing mounted on a base which is mounted on a trunnion of the receiver. The housing defines an aperture and includes a sight post extending upwardly in the front sight aperture.
The rear sight of this aforesaid arrangement is attached to the upper receiver. The upright bracket may be attached to a rod which is operatively connected to a screw for rotation of the rod, and therefore, lateral movement of the bracket within the trunnion. The upright bracket may have an elongated slot having a slidable aperture and calibration marks along one of its surfaces for positioning the aperture relative to a target. The aperture is attached to an elevational screw which slides on a rail for setting the elevation and a leaf assembly transverses the screw on the bottom.
A disadvantage of the sighting system of the aforesaid arrangement for a machine gun is that the upright bracket of the rear sight can easily become askew on its threaded rod when the machine gun is being fired such that the aperture also becomes askew, thereby disturbing the line-of-sight of the target. A further disadvantage is that the rear sight does not provide different apertures for varying distant targets.
Additional examples of rear and/or front sights for various types of fire arms are disclosed in U.S. Pat. Nos. 4,127,943; 4,536,966; 5,930,906; 5,983,774; 6,860,056 B2; 6,968,643 B2; and 7,181,882 B2.
U.S. Pat. No. 7,181,882 B2 discloses a sighting system for a shotgun having a rear sight and a front sight. The rear sight has sight elements adaptable for “zeroing in” the same gun with different ammunition. The rear sight has windage and elevation adjustments for the sight elements so that multiple ammunition types having different trajectories may be fired accurately from a single firearm after zeroing in one of the sight elements for each of the different ammunition types. The sight elements may be connected to each other or to a common pivot arm or movable bracket so that moving one sight element into the sight path automatically removes the other from the line of vision. In one embodiment, one of the elements of the rear sight is a hollow ghost ring used to align shots taken with buckshot-type ammunition and another element is a V-shaped notch used to align shots taken with slug loads. These elements are attached to a pivoting L-shaped mount and form a single pivoting unit and are separated by a right angle. Consequently, flipping the V-shaped notch into the line-of-sight pivots the ghost ring out of the sight plane and vice versa. Applying slight pressure to the pivoting system flips the sights and claps, or other mechanisms may be desirable to fix the sights in a given position.
This design for the sighting system for a shotgun as disclosed in the above U.S. Pat. No. 7,181,882 B2 may be adequate for a shotgun and the other sighting systems of the prior art listed hereinabove may be adequate for the type of firearm they are used on; however, these sighting systems prove to be ineffective when used on a machine gun. That is, the sighting system for use on a machine gun needs to have a greater degree of adjustability for setting up a line-of-sight for a target. Also, since a machine gun is designed for continuous use and is a powerful, heavy weapon weighing close to 100 pounds, it creates a great thrust when operated. Also, the sights, particularly the rear sight close to the operator of the machine gun, needs to remain in place when the machine gun is continuously being fired so that the line-of-sight remains accurate even though the target may be moving quickly.
There is a need, therefore, in the art pertaining to machine guns, such as an M2HB, M3 flexible, which are 50 caliber machine guns, for an improved design of a sighting system having a front sight assembly and a rear sight assembly which allows for an increase in the percentage of hit rounds when the machine gun is operated and which also allows for a greater degree of adjustability compared to the prior art sighting systems used on firearms, including those described hereinabove.